Apparatus and method for trailer service brake control

ABSTRACT

A system on a tractor for controlling trailer service brakes comprises a manually operated trailer brake switch, a first electropneumatic valve in communication with a pressure source and a controller. The controller has an input communicating with the trailer brake switch, an output communicating with the electropneumatic valve and control logic. The control logic receives an input from the trailer brake switch indicating a driver&#39;s request to apply the trailer service brakes of the combination vehicle, determines if a predetermined condition exists and transmits a signal to the output to the electropneumatic valve. The electropneumatic valve transmits pressure to a trailer service control line to actuate the trailer service brakes in response to the trailer brake switch and existence of the predetermined condition.

BACKGROUND

The present invention relates to examples of a control device for trailer service brakes and method of controlling trailer service brakes. Today's air brake systems on commercial vehicles include multiple pneumatic valves used to provide air to the service brakes of both the tractor and the trailer. One example valve to actuate the trailer service brakes is a trailer control valve, such as the TCS-9000™ control brake valve available from Bendix Commercial Vehicle Systems LLC, Elyria Ohio. The trailer control valve is located in the cab of a tractor and includes a handle. The driver of the commercial vehicle activates this valve when he wants to operate the trailer service brakes independently of the tractor service brakes. The air control lines must be routed through the dash of the cab in order for the driver to actuate the trailer service brakes by hand. In some safety situations, drivers should not be permitted to activate only the trailer service brakes. There is a need to eliminate air running through the dash of commercial vehicles while still maintaining driver features, such as independent control of the trailer service brakes, in limited situations.

SUMMARY

Various examples of a system on a tractor for controlling trailer service brakes comprises a manually operated trailer brake switch, a first electropneumatic valve in communication with a pressure source and a controller. The controller has an input communicating with the trailer brake switch, an output communicating with the first electropneumatic valve and control logic. The control logic receives an input from the trailer brake switch indicating a driver's request to apply the trailer service brakes of the combination vehicle, determines if a predetermined condition exists and transmits a signal to the output to the first electropneumatic valve, wherein the first electropneumatic valve transmits pressure to a trailer service control line to actuate the trailer service brakes in response to the trailer brake switch and existence of the predetermined condition.

Various examples of a system on a tractor for controlling trailer service brakes comprise a manually operated trailer brake switch and a controller. The control logic of the controller receives an input from the trailer brake switch indicating a driver's request to apply the trailer service brakes of the combination vehicle, determines if a predetermined condition exists and transmits pressure to a trailer service control line to actuate the trailer service brakes in response to the trailer brake switch and existence of the predetermined condition.

Various examples of a method for controlling trailer service brakes comprises receiving an input from a trailer brake switch indicating a request to apply trailer service brakes, determining whether the vehicle meets a predetermined condition and transmitting a signal to the output to an electropneumatic valve to actuate the trailer service brakes in response to the activation of the trailer brake switch and the speed being less than a predetermined speed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the embodiments of this invention.

FIG. 1 illustrates a schematic representation of an example tractor service braking system and a trailer service braking system on a commercial vehicle.

FIG. 2 illustrates a schematic representation of a tractor service braking system and a trailer service braking system on a commercial vehicle according to another example.

FIG. 3 illustrates a method of operating the trailer service brakes according to an example of the present invention.

DETAILED DESCRIPTION

With reference to FIG. 1, a tractor service braking system 10 and trailer service braking system 12 of an air braked commercial vehicle is illustrated.

The tractor system 10 includes a service brake foot valve 34 for receiving a driver's request to stop or slow the entire vehicle. The foot valve 34 receives supply air pressure from a reservoir 26 and delivers the driver requested delivery pressure to a front axle valve 32, a rear axle valve 36 and a first input 68 of a tractor protection valve 64. The front axle valve 32 will deliver the pressure to the front service brakes 33, the rear axle valve 36 will deliver the pressure to the rear axle service brakes 37 and the tractor protection valve 64 will deliver the pressure to the trailer service braking system 12.

The tractor service braking system 10 communicates with the trailer service braking system 12 through the tractor protection valve 64. The tractor protection valve 64 has the first input 68 and a second input 66. The tractor protection valve 64 communicates the control pressure of the highest value of either the first input 68 or the second input 66 to the trailer system 12 while protecting the air in the tractor system 10 in case of separation of the connection between the tractor system 10 and trailer system 12. The tractor protection valve 64 communicates with a trailer control pressure line 38. The trailer control pressure line 38 communicates via gladhand 72 to gladhand 76 of the trailer system 12. Gladhand 76 communicates with the trailer control pressure line 84 of the trailer system 12. The tractor protection valve 64 communicates with a trailer supply pressure line 39. The trailer supply pressure line 39 communicates with gladhand 74 to gladhand 78 of the trailer system 12. Gladhand 78 communicates with the trailer supply pressure line 86.

In the trailer system 12, the trailer supply pressure line 86 communicates with a trailer reservoir 82. The trailer control pressure line 84 communicates with a trailer control valve device 80 mounted on the trailer. The control valve device 80 performs service braking functions. The service brakes on the trailer are actuated in response to the pressure received on the trailer control pressure line 84 as long as sufficient pressure is available in the trailer reservoir 82.

The tractor system 10 includes a trailer control switch 14. The trailer control switch 14 is manually operated by a driver from inside a cab of the tractor. The trailer control switch 14 is electronic and may be a two state switch or alternatively a three state switch with on-hold-off states. The trailer control switch 14 may be installed in a dashboard panel or may be attached to the steering column. The trailer control switch 14 is used by the driver when he only wants to apply the trailer service brakes and not the tractor service brakes.

The tractor system 10 includes a first electropneumatic valve 16. The first electropneumatic valve may be a 3/2 solenoid operated valve. The first electropneumatic valve 16 receives supply air pressure from the reservoir 26 at a supply input 18. The first electropneumatic valve 16 communicates pneumatically with the front axle valve 32 at input 24 and transmits control pressure at output 20 to the second input 66 of the tractor protection valve 64.

The tractor system 10 may include a second electropneumatic valve 56. The second electropneumatic valve 56 may be an anti-lock brake system pressure modulator valve. An input 58 of the second electropneumatic valve 56 would communicate pneumatically with the output 20 of the first electropneumatic valve 16. An output 60 would communication with the second input 66 of the tractor protection valve 64.

The tractor system 10 includes a controller 40. The controller 40 includes a processor with control logic 42 for receiving and transmitting messages. The control logic 42 may also receive sensor signals and transmit control signals to control the tractor service brake system 10 of the vehicle. The control logic 42 may include volatile, non-volatile memory, solid state memory, flash memory, random-access memory (RAM), read-only memory (ROM), electronic erasable programmable read-only memory (EEPROM), variants of the foregoing memory types, combinations thereof, and/or any other type(s) of memory suitable for providing the described functionality and/or storing computer-executable instructions for execution by the control logic 42. The controller 40 may perform anti-lock brake functions, stability control functions and automated driver assist functions. In one example, the controller 40 may be integrated with another vehicle controller on the tractor.

The controller 40 receives signals at input 50 from the trailer control switch 14. The input indicates a driver's desire to actuate the service brakes of the trailer system 12 independent of the tractor service brakes. Alternatively, the controller 40 receives the request via a serial vehicle communications bus 30 or from a source other than the driver.

The controller 40 receives signals at input 48 from a wheel speed sensing device, illustrated as wheel speed sensor 28. It is understood that more than one wheel speed sensor may be installed as part of the tractor system 10 in order to determine vehicle speed. Each wheel speed sensor is connected to the controller 40. The control logic 42 determines vehicle speed in response to the wheel speed sensor signals. Alternatively, the controller 40 includes a communications port 46 and communicates on the vehicle communications bus 30 to receive the vehicle speed from another source, such as the engine.

The controller 40 receives signals at input 43 from a pressure sensing device, illustrated as pressure sensor 70. The pressure sensor 70 is in pneumatic communication with the reservoir 26. The control logic 42 determines available supply pressure in response to the pressure signal. It is understood that more than one pressure sensor may installed as part of the tractor system 10 in order to determine available supply pressure. Each pressure sensor is connected to the controller 40. Alternatively, the controller 40 communicates on the vehicle communications bus 30 to receive the pressure information from another source, such as a vehicle electronic air control system.

The controller 40 electrically communicates with the front axle valve 32 and the rear axle valve 36 to autonomously actuate the tractor service brakes in certain stability control situations. The controller 40 may communicate control signals via the vehicle communications bus 30 or via dedicated outputs to each valve.

The controller 40 electrically communicates with the first electropneumatic valve 16 at the output 44 to actuate the trailer service brakes in situations where the driver may request a trailer service brake actuation but not a tractor service brake application. No input is required from the foot valve 34. The controller 40 receives a signal at input 50 from the trailer brake switch 14 in response to the driver's request to only actuate the trailer service brakes. These situations may occur when a tractor driver is positioning the tractor to be mechanically connected to the trailer or when the driver desires to perform a pre-trip inspection of the trailer service braking system.

The controller 40 transmits a control signal at output 44 in response to the request to actuate only the trailer service brakes. The first electropneumatic valve 16 opens a path from the reservoir 26 to output 20 to provide supply pressure, thereby delivering control pressure to the tractor protection valve 64. The tractor protection valve 64 will transmit the control pressure to tractor control line 38 and onto the trailer service brake system 12 as long as a trailer is connected to the tractor. The controller 40 will also discontinue the signal to the first electropneumatic valve 16 when actuation of the trailer service brakes is no longer desired by the driver based on the input from the trailer brake switch 14 or when certain predetermined conditions are not met.

In instances where fine pressure control or less than full supply pressure is desired at the trailer service brakes, the controller 40 electrically communicates at output 45 with the second electropneumatic valve 56. Full pressure may be desired if the vehicle is on an incline, but may not be necessary if the vehicle is on a flat surface. Reducing the pressure to the brake system will preserve the life of the brake components. The second electropneumatic valve 56 will receive the control pressure from the first electropneumatic valve 16 and cycle the solenoids to provide varying amounts of air to the second input 66 of the tractor protection valve 64. The tractor protection valve 64 will transmit the control pressure to the tractor control line 38 and into the trailer service brake system 12 as long as a trailer is connected to the tractor. Alternatively, a pneumatic only pressure reduction valve could be used in place of the second electropneumatic valve 56.

The controller 40 may also communicate with an indicator 54. The indicator 54 may be a lamp in the dash of the vehicle or a dashboard display. The indicator 54 shows the driver the operating state of the trailer service brake system.

Therefore, a system on a tractor for controlling trailer service brakes comprises a manually operated trailer brake switch, a first electropneumatic valve in communication with a pressure source and a controller. The controller has an input communicating with the trailer brake switch, an output communicating with the first electropneumatic valve and control logic. The control logic receives an input from the trailer brake switch indicating a driver's request to apply the trailer service brakes of the combination vehicle; determines if a predetermined condition exists, and transmits a signal to the output to the first electropneumatic valve, wherein the first electropneumatic valve transmits pressure to a trailer service control line to actuate the trailer service brakes in response to the trailer brake switch and existence of the predetermined condition.

With reference to FIG. 2, a tractor service braking system 10′ and a trailer service braking system 12′ of an air braked commercial vehicle showing another example embodiment of the invention is illustrated. Elements that are the same as in FIG. 1 have the same numbers.

The tractor system 10′ includes the service brake foot valve 34 for receiving a driver's request to stop or slow the vehicle. The foot valve 34 receives supply air pressure from the reservoir 26 and delivers the driver requested delivery pressure to the front axle valve 32, the rear axle valve 36 and the first input 68 of the tractor protection valve 64. The front axle valve 32 will deliver the pressure to the front service brakes 33 as well as to the second input of the tractor protection valve 64. The rear axle valve 36 will deliver the pressure to the rear axle service brakes 37 and the tractor protection valve 64 will deliver the pressure to the trailer service braking system 12′.

The tractor service braking system 10′ communicates with the trailer service braking system 12′ through the tractor protection valve 64. The tractor protection valve 64 communicates the control pressure at either the first input 68 or the second input 66 having the highest pressure value to the trailer system 12′ while protecting the tractor system 10′ in case of separation of the connection between the tractor system 10′ and trailer system 12′. The tractor protection valve 64 communicates with the trailer control pressure line 38. The trailer control pressure line 38 communicates via gladhand 72 to gladhand 76 of the trailer system 12′. Gladhand 76 communicates with the trailer control pressure line 84. The tractor protection valve 64 communicates with a trailer supply pressure line 39. The trailer supply pressure line 39 communicates with gladhand 74 to gladhand 78 of the trailer. Gladhand 78 communicates with the trailer supply pressure line 86.

The trailer supply pressure line 86 communicates with a trailer reservoir 82. The trailer control pressure line 84 communicates with a control valve device 80 mounted on the trailer. The control valve device 80 performs service braking functions. The service brakes on the trailer are actuated in response to the pressure received on the trailer control pressure line 84 or automatically in response to a signal from the tractor system 10′, as will be disclosed.

The tractor system 10′ includes the trailer control switch 14. The trailer control switch 14 is manually operated by a driver from inside a cab of the tractor. The trailer control switch 14 is electronic and may be a two state switch or alternatively a three state switch with on-hold-off states. The trailer control switch 14 may be installed in a dashboard panel or may be attached to the steering column. The trailer control switch 14 is used by the driver when he only wants to apply the trailer service brakes and not the tractor service brakes.

The tractor system 10′ includes the controller 40. The controller 40 includes a processor with control logic 42 for receiving and transmitting messages. The control logic 42 may also receive sensor signals and transmit control signals to control the tractor service brake system 10′ and the trailer service brake system 12′ of the vehicle. The control logic 42 may include volatile, non-volatile memory, solid state memory, flash memory, random-access memory (RAM), read-only memory (ROM), electronic erasable programmable read-only memory (EEPROM), variants of the foregoing memory types, combinations thereof, and/or any other type(s) of memory suitable for providing the described functionality and/or storing computer-executable instructions for execution by the control logic 42. The controller 40 may perform anti-lock brake functions, stability control functions and automated driver assist functions.

The controller 40 receives signals at input 48 from the wheel speed sensing device, illustrated as wheel speed sensor 28. It is understood that more than one wheel speed sensor may be installed as part of the tractor system 10 in order to determine vehicle speed. Each wheel speed sensor is connected to the controller 40. The control logic 42 determines vehicle speed in response to the wheel speed sensor signals. Alternatively, the controller 40 includes a communications port 46 and communicates on a vehicle communications bus 30 to receive the vehicle speed from another source, such as the engine.

The controller 40 receives signals at input 43 from the pressure sensing device, illustrated as pressure sensor 70. The pressure sensor 70 is in pneumatic communication with the reservoir 26. The control logic 42 determines available supply pressure in response to the pressure signal. It is understood that more than one pressure sensor may installed as part of the tractor system 10′ in order to determine available supply pressure. Each pressure sensor is connected to the controller 40. Alternatively, the controller 40 communicates on the vehicle communications bus 30 to receive the pressure information from another source, such as a vehicle electronic air control system.

The controller 40 electrically communicates with the front axle valve 32 and the rear axle valve 36 to autonomously actuate the tractor service brakes in certain stability control situations. The controller 40 may communicate control signals via the communications bus 30 or via a dedicated output.

The tractor system 10′ includes a communication line 92. The communication line may be a controller area network line or a power line carrier bus that will transmit control signals on the communication line 92 of the tractor system 10′ through an electrical connector 95 to the communication line 94 of the trailer system 12′. The controller 40 electrically communicates with the trailer control valve 80 via the communication line 92. Alternatively, the controller 40 may communicate wirelessly with the trailer control valve 80. The controller 40 will transmit a signal or message such that the trailer control valve 80 will respond by actuating the trailer service brakes. No pneumatic signal is transmitted between the tractor system 10′ and the trailer system 12′. Fine pressure control of the trailer system 12′ can be achieved by changing the transmitted signal or the messages.

The controller 40 may also communicate with the indicator 54. The indicator 54 may be a lamp in the dash of the vehicle or a dashboard display. The indicator 54 shows the driver the operating state of the trailer service brake system 12′.

FIG. 3 illustrates a flowchart for implementing a method 100 of controlling the trailer service brakes using the systems of FIG. 1. The method 100 begins at step 102. In step 104, the driver activates the trailer brake switch 14, indicating his desire to apply only the trailer service brakes.

In step 106, the control logic 42 determines if a predetermined condition is met. In one example, the predetermined condition is whether the speed of the tractor is less than a predetermined speed. The predetermined speed may be about five miles per hour. This low speed ensures that the tractor is fully stopped or nearly stopped. In another example, the predetermined condition is a pressure value from the pressure sensor being greater than a predetermined pressure. The predetermined pressure may be about sixty psi. Other examples of predetermined conditions include the presence of a trailer, the trailer parking brake status, such that if the trailer is parked, there is no need to activate trailer service brakes, and whether the transmission is in neutral or low gear. In addition, a geofence may be implemented to prevent the service brake activation outside the geofence.

In another example, the control logic 42 may consider a time out as a predetermined condition. The control logic 42 would not allow the trailer service brakes to be activated for longer than a predetermined period of time after the trailer brake switch 14 is activated. Each of the initial predetermined conditions must still be met to allow the service brakes to be applied. The predetermined period of time may be between one and three minutes. Other implementations of predetermined conditions are also possible.

In one example, if none of the predetermined conditions are met and there is no additional driver intervention, the trailer service brakes are released and the trailer parking brakes would be automatically applied to ensure that the trailer remains stationary.

If the predetermined condition is not met, the driver receives an indication in step 108. The indication may be via the indicator 54. The indicator 54 may be lit only when the trailer service braking system 12 is actuated and may blink if a request for service brakes was made via the trailer brake switch 14 but the predetermined condition was not met. Other methods of indicating the status of the trailer service braking system to the driver, such as LCD displays and audible means are contemplated. The method 100 then returns to the start step 102.

If the predetermined condition is met, the method 100 continues to step 110. In another example, one or more of the predetermined conditions must be met. The control logic 42 transmits a control signal to activate the trailer service brakes. The control signal includes transmitting a signal at output 44 to activate the first electropneumatic valve 16 so that air pressure will flow to the second input 66 of the tractor protection valve 64, through the tractor control line 38 and into the trailer control line 84.

If the second electropneumatic valve 60 is present in the system, then the control logic 42 will transmit a signal to both the first electropneumatic valve 16 and the second electropneumatic valve 56. The signal to the second electropneumatic valve 56 is adjusted, such as pulse width modulated, to provide less than the full available delivery pressure to the trailer service braking system 12. The control logic 42 will maintain the trailer service brakes as actuated as long as the trailer brake switch 14 is in the active state, a predetermined condition is no longer met or until the trailer brake switch 14 is moved to the off position if the trailer brake switch 14 returns to neutral after actuation. Alternatively, the function of the second electropneumatic valve to deliver a tunable pressure value can be combined into the first electropneumatic valve 16 such that only one valve is used.

The control logic 42 continuously monitors the vehicle conditions, such as speed and supply pressure. If the vehicle condition changes such that the predetermined condition is no longer met as in step 112, the trailer service brakes are released in step 114 where the control logic no longer transmits a signal to the first electropneumatic valve 16 or the second electropneumatic valve 56, which will discontinue the control pressure supplied to the trailer service braking system 12. In one example, if none of the predetermined conditions are met and there is no additional driver intervention, the trailer parking brakes would be automatically applied to ensure that the trailer remains stationary.

With this method of operating the trailer service brakes, the driver cannot abuse the trailer service braking system by using the trailer service brakes during on the road driving situations since the operation is limited to low speed operation. The trailer service brakes will not be activated if the available pressure is not at a predetermined minimum. Neither will the driver be able to leave the trailer service brakes activated indefinitely using the system of the present invention.

Therefore a method of controlling trailer service brakes comprises receiving an input from a trailer brake switch indicating a request to apply trailer service brakes; determining whether the vehicle meets a predetermined condition; transmitting a signal to the output to an electropneumatic valve to actuate the trailer service brakes in response to the activation of the trailer brake switch and the speed being less than a predetermined speed.

While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept. 

We claim:
 1. A system on a tractor for controlling trailer service brakes comprising: a manually operated trailer brake switch; a first electropneumatic valve in communication with a pressure source on the tractor; and a controller, the controller having: an input communicating with the trailer brake switch; an output communicating with the first electropneumatic valve; and control logic, the control logic: receiving an input from the trailer brake switch indicating a driver's request to apply the trailer service brakes of the combination vehicle; determining if a predetermined condition exists; and transmitting a signal to the output to the first electropneumatic valve, wherein the first electropneumatic valve transmits pressure to a trailer service control line to actuate the trailer service brakes in response to the trailer brake switch and existence of the predetermined condition.
 2. The system as in claim 1, wherein the predetermined condition is one or more of a speed of the tractor being less than a predetermined speed and a pressure at the pressure source being greater than a predetermined pressure.
 3. The system as in claim 2, wherein the predetermined speed is about five miles per hour.
 4. The system as in claim 2, wherein the predetermined pressure is about sixty psi.
 5. The system as in claim 1, the controller further having a communications port for receiving signals regarding the predetermined condition.
 6. The system as in claim 1, the control logic further transmitting a signal to the output to the electropneumatic valve to release the trailer service brakes in response to the predetermined condition not being met.
 7. The system as in claim 1, further comprising an indicator, wherein the control logic transmits a signal to the indicator to indicate the status of the trailer service brakes.
 8. The system as in claim 1, the control logic further transmitting a signal to the output to the first electropneumatic valve to maintain the trailer service brakes as actuated in response to the trailer brake switch being maintained in the active position and a speed of the combination vehicle being less than a predetermined speed.
 9. The system as in claim 8, wherein the first electropneumatic valve deactuates the trailer service brakes after a predetermined time period from actuation.
 10. The system as in claim 1, wherein the controller is integrated with another vehicle controller.
 11. The system as in claim 1, further comprising a second valve, wherein the second valve communicates pneumatically with the first electropneumatic valve and the trailer service control line to reduce the pressure delivered to the trailer service brakes.
 12. The system as in claim 11, wherein the second valve is a second electropneumatic valve, wherein the control logic transmits a signal to the second electropneumatic valve to variably control the amount of pressure delivered to the trailer service brakes.
 13. The system as in claim 11, wherein the second valve is a pneumatic reduction valve.
 14. A method for controlling trailer service brakes comprising: receiving an input from a trailer brake switch indicating a request to apply trailer service brakes; determining whether the vehicle meets a predetermined condition; transmitting a signal to actuate the trailer service brakes in response to the activation of the trailer brake switch and the existence of the predetermined condition.
 15. The method as in claim 14, wherein the predetermined condition is one or more of a speed of the tractor being less than a predetermined speed, a time period from actuation being less than a predetermined time period and a supply pressure being greater than a predetermined pressure.
 16. The method as in claim 15, wherein the predetermined speed is about five miles per hour.
 17. The method as in claim 15, wherein the predetermined pressure is about sixty psi.
 18. The method as in claim 15, wherein the predetermined time period is about three minutes.
 19. The method as in claim 14, further comprising indicating the status of the trailer service brakes to the driver.
 20. The method as in claim 14, wherein transmitting a signal to actuate the trailer service brakes comprises actuating a first electropneumatic valve and a second valve.
 21. The method as in claim 14, wherein transmitting a signal comprises transmitting a wireless signal to actuate the trailer service brakes.
 22. A system on a tractor for controlling trailer service brakes comprising: means for receiving a request to activate the trailer service brakes; means for determining a predetermined condition of a vehicle; and means for transmitting pressure to a trailer service braking system to actuate the trailer service brakes independent of the tractor service brakes in response to the request to activate the trailer service brakes and the predetermined condition being at least one of the speed of the vehicle being less than a predetermined speed, the supply pressure of the tractor being greater than a predetermined pressure and a time period from actuation of the trailer service brakes being less than a predetermined time period. 